Ribulose-biphosphate carboxylase (rbcL) sequences representing almost all the tribes currently recognized in Rubiaceae plus ca. 260 other asterid genera are available in GenBank. Cladistic analyses of subsets of these data have been published addressing important aspects of the classification of Rubiaceae. Investigation of all these sequences in larger analyses that allow us to test global maximum parsimony is now possible due to the existence of highly efficient software (Nona for Windows NT: Goloboff, 1997). The present study compares the results from rbcL partial analyses (local parsimony) of infra-familiar taxa in Rubiaceae to those with: 1.- 146 sequences of Rubiaceae plus 3 asterid outgroups, and 2.- the 149-taxon Rubiaceae matrix plus 260 asterid genera and 30 tricolpate outgroups. The 149-taxon analyses contained 405 potentially informative sites and yielded 49,248 equally most parsimonious trees (L=2,377, Ci= 0.26, Ri=0.76). The 439-taxon analyses contained 637 potentially informative sites and yielded 50,000 (filled memory) equally most parsimonious trees (L=8,363, Ci=0.14, Ri=0.73). The gross topology of the consensus trees in the three groups of analyses was similar, but the position of some taxa differed. In the context of rbcL sequences, the larger sample provided more rigorous tests of monophyly for particular clades. One problem of increasing the number of taxa for a particular kind of data (rbcL in this case) is the proportional reduction of potentially informative characters per taxon: in these analyses, 2.72 (for 149 taxa), 1.45 (for 439 taxa), and 0.91 (for 910 taxa; not reported here). At the same time, the larger sample resulted in less resolution within the main clades. Because of the possibility of conducting analyses with relatively large data sets, decisions on sample size should be made on the basis of the aims of the research rather than on software/time limitations due to a preferred computer platform.

Key words: Asteriidae, cladistics, classification, Local and global parsimony, rbcL, Rubiaceae